As has already been stated you can not make a child be homosexual. This is as harmful as trying to make a homosexual child be heterosexual. You can't decide a child's sexuality and trying to will only cause emotional harm to the child. If you want to raise a homosexual child adopt one! There are many in need of homes from supportive families, it's not hard to adopt a child and it will help them.

As to the gender-neutral parenting, it sounds wonderful in theory, in practice not so much. A child should never be raised with an expectation to fit a gender norm, they should be encourage to play with whatever they want to play with, be it dolls or cars or something else that doesn't fit the gender norm, and to enjoy whatever colors they enjoy, be it pink or blue. A boy should be raised to be aware of his emotions and free to express them, just as a girl should be raised to not be afraid to get dirty or be physically active. Children should be encouraged to be whoever they are without regard to their physical sex and freely exposed to activities and options associated with both gender norms.

However, trying to hide your child's physical sex will do far more harm then good! I get the concept, in theory it would be great to prevent anyone from applying gender roles to the child, but in reality it just doesn't work.

For starters your child will know his/her physical sex, and will see that media and society expect something from a child of that sex, so they will likely still be exposed to almost as much societal stereotypes. children raised gender neutral usually end up with the same gender role as their physical sex and quite sterotypical. How much of that is biological (there are very real biological factors to gender identity that play a significant role in how one's gender develops) and how much is due to their internalizing societal roles by seeing them applied to other's of the same gender is unclear, but the end result is that they usually grow up with the same gender identity after all that work.

However, they go through far more difficulty getting there. Childern raised gender-neutral are more likely to feel conflicted about gender roles, more likely to feel they don't fit either role or even express concern that they are 'wrong' for confirming with the gender role of their sex despite the efforts of raising them gender-neutral.

All that time spent telling a child they shouldn't reveal their physical sex works to make their sex a guilty secret. They can't develop a proper gender identity because they are told it's 'wrong' to confirm to one. The intent is good, but it just causes the child to feel something is wrong with their sex/gender because they can't reveal it despite people asking for it, and this leads to confusion later.

While I wish society was different, the fact is raising a gender-neutral child also means facing bullying, for both you and your child. I will say flat out that this shouldn't happen, not in a a proper and idealized society, but reality isn't that society. Raising a child gender-neutral means more bullying for that child when he is young, and for you. It means him/her having to go through discussions as to why they can't reveal their identity. It means extra drama and emotional difficulty caused by society that isn't supportive of what is being attempted. This could be worth it, if the benefit for the child was enough, but I don't see much actual benefit done to justify it.

in the end what is the best case scenario of raising a child gender-neutral? If they happen to be transgendered anyways it would no doubt help them with their transition to the opposite gender, but only a tiny fraction of children will be transgendered, so the vast majority of the time this won't be relevant. If the child isn't transgendered then what do they gain for all this difficulty? In theory it's that they feel more comfortable demonstrating non gender-normative traits that they may otherwise have felt bad expressing, but if you simply encourage a child to demonstrate their traits without hiding their physical sex you gain this same benefit without all the difficulty of gender-nutral lifestyle, and all the risk of confusing the child.

In short there is just too much risk of making the child unsure or guilty about their sex/gender and too little benefit for the majority of children to make it worth doing.

As to why your wife wants this, if I had to guess I would suspect that she wants to show she is 'supportive' of alternative lifestyles and genders, which is fine. It's good to be supportive of these. However, the fact is that the majority of children will not grow up to have a non-traditional gender/sexuality/lifestyle. Trying to create an enviroment where a child can express any non-traditional inclination freely is good, trying to expect or force it when it's unlikely to come up is potentially harmful if not done very carefully because it can make the child fill guilty for being traditional.

I suggest a few things to do to work this out with your wife, in addition to what is already mentioned. First, discuss how you can support your child's ability to express non-traditional predisposition without needing to go to extremes. Set plans for how to encourage your child to not feel pressured by gender norms without resorting to gender-neutral extreme. For example you could set plans like these:

Originally buying toys traditionally intended for both genders so the child is exposed and to and feels free to play with either; though you should transition to buying the toys the child enjoys as the child grows old enough to express this.

Make plans to expose the child to people with non-traditional lifestyles, including different sexuality or gender then is traditional, to demonstrate that these are acceptable options for your child.

Make plans for how to speak with the child to avoid imposing stereotypes in your talk, such as including both sexes when you talk about theoretical person they may be interested in dating when they get older.

Plan to dress the child gender-neturally. This means avoiding blue/pink (or putting them in the non-traditional color), but also includes using gender-neutral hair cut and controlling what jewelry/ear-ring they wear etc. If a stranger is unsure what sex the child is they are unlikely to impose gender stereotypes on the child. However, this doesn't risk the same harm as gender-neutral parenting because you don't force the child to hide their sex like it's a secret. Your keeping strangers guessing without the child realizing that your doing it, but at no point are you expressing to the child that their sex is a dirty secret that should not be revealed if asked.

The point of these examples is to show all the ways you can raise the child in a way that doesn't impose gender stereotypes without having to go so far as to hide the child's sex, which can make the child feel guilty about that sex. These can all be positive optoins for your child anyways; However, you must go in with the understanding that your child will start to express their own identity early and you should transition to support that identity, including letting them pick how they should look and what toys they will play with, as soon as the child starts to express a preference!!

By discussing these sort of goals early you can help demonstrate to your wife how she can meet her goals of encouraging the child without going to such an extreme as to cause potential harm by accidentally trying to force some non-traditional inclination that doesn't exist in the child.

In my experience people who express these wishes also sometimes do it because they want to be seen as open to other sexuality/genders. In other words it may not just be about supporting the child, but being seen openly as doing it so friends will know how very supportive your wife is. That may sound harsh when said like that, let me stress it is not meant as such; this is not an uncommon motivation for actions even if we don't usually admit it. Thus finding ways to openly support people with non-traditional stereotypes/genders other then trying to push your child towards it could be useful. This means things like going to gay pride or volunteering with gay/lesbian/trans charities. www.volunteermatch.org is a good place to look to find such organizations. This can give your wife a great way to demonstrate her support, and further demonstrate to your child(ren) how supportive you are as they grow older and see the work your doing.