Christine Cheung wonders if there will be a day where she could go about her life without being asked if Lucas is her real son.

She had her husband Aaron, who are both of Asian descent, welcomed their first child two years ago but were shocked to find that he had a rare medical condition - one that is believed to have only struck two families in Australia.

The main symptoms being that Lucas had intractable diarrhoea, an immune deficiency and blonde hair.

But the Cheungs - who live in Riverview in Sydney's north shore - say they are approached by strangers at least three times a day, intrigued to learn about Lucas' biological history.

On many occasions, Mrs Cheung says has been left frustrated and angered by questions which imply her son does not belong to her.

Christine Cheung with her two-year-old son Lucas who has tricho hepato enteric syndrome which includes symptoms such as blonde hair

It took doctors one and a half years after Lucas was born that doctors were able to diagnose him with the rare medical condition

'It took us a year and a half to find out what medical condition Lucas had and the doctors had never heard of such a case,' Mrs Cheung told Daily Mail Australia.

Lucas has tricho hepato enteric syndrome - a disorder which has only ever been reported 44 times worldwide.

Needless to say, it was an arduous time for the first-time parents as Mr and Mrs Cheung were desperate for some kind of diagnosis for their son who was born prematurely at 32 weeks.

'We had to go through test after test which kept coming back negative so we were pretty much living in the hospital for a year and a half,' Mrs Cheung said.

'It was painful but in the end we were so happy to finally get an answer.'

However the Cheungs were faced with the reality that there was limited information and research surrounding the uncommon illness.

There are reportedly only two families in Australia, seven around the world, who have tricho hepato enteric syndrome.

'We actually went and visited the one other family in Australia who have a child with the same condition as Lucas,' she said.

'We're lucky in a way to know that there's another family in Australia who's going through the same thing as us.

'From what we know, and with the minimal information that we have, we're the first Asian family in Australia to have the syndrome so far.'

Little Lucas was born prematurely at 32 weeks and had to be kept in hospital for a year and a half

Due to Lucas' rare disorder, he was unable to digest anything as he had intractable diarrhoea

Mrs Cheung says her son's symptoms are now manageable and he's becoming more healthy each day

While Mrs Cheung, 32, tends to her child's medical needs as he has trouble digesting food, she also has to deal with the multiple questions and assumptions made about why her son naturally has platinum blonde hair.

'Nobody knows about his condition because there's not much research about it,' she said.

'Lucas' symptoms are now manageable but he used to get diarrhoea about 30 to 45 times a day.'

So her annoyance is understandable when she is constantly questioned by strangers, who most which are quite presumptuous and rude.

'It depends how I'm approached but unfortunately most of the time I get asked "was he born like that?" or "why is he blonde" and they're all asked in a judgemental tone so that's why I react in a negative way,' she said.

'It's as if they're asking me whether he's been adopted. Actually, I was even asked by this one woman: "is he your real son?".'

'I feel that when I'm asked in a rude way that the information is really none of their business and I'm seriously so sick of the questions.'

(From left) Husband Aaron Cheung, little Lucas and mum Christine Cheung

Mr Cheung, 34, spending some quality time with his first child Lucas

While Mrs Cheung recognises the natural curiosity of others, she wants people to think before they jump to conclusions.

'I'm not exaggerating when I say that I get asked minimum three times a day,' she said.

'But I get it, Lucas stands out. He has blonde hair and I've even given him a trendy haircut because I love his hair and want to make the most of it.

'I know where people are coming from but they should think before they ask such rude questions and if they were more polite about it then I'm happy to respond.'

Yet in a more recent incident, Mrs Cheung was at a restaurant with her family when another diner interrupted her meal and questioned her about Lucas.

'She stopped eating and came straight up to our table and asked me: "why is he blonde?". She didn't even say hello or anything,' she said.

'If she had approached me in a more polite way I wouldn't have been so angry about it.'

Ever since Lucas came into her life, Mrs Cheung's outlook on life has changed.

'I know that if I saw someone looking a little different on the street that I wouldn't go up and ask them about it - it's their life and it's personal,' she said.

'My dream goal is to help mums with sick kids or children with special needs because I've been through it all.

'Some people think we should appreciate it that we're being given special attention when all we really want is to be treated like any other person.