not true. actual transcript from the source (which by the way is NOT her website, it’s the Leaky Cauldron, a fan site: http://the-leaky-cauldron.org/2007/7/30/j-k-rowling-web-chat-transcript) (emphasis mine):

Ravleen: How much does the fact that voldemort was conceived under a love potion have to do with his nonability to understand love is it more symbolic

J.K. Rowling: It was a symbolic way of showing that he came from a loveless union – but of course, everything would have changed if Merope had survived and raised him herself and loved him.

so you see, fans put these ideas together, not rowling. rowling did not confirm this so much as mention that the love potion was symbolic of an environment where love was lacking. “symbolic” is a key word there. it was not meant to imply that being conceived with a love potion, or rape, or a one-night stand, is a direct cause of an inability to ever love at all. i doubt rowling would be pushing that agenda. she even mentions that, love potion or no, a mother’s love would have been a key factor in voldy’s ability to understand the concept. surely though, if merope HAD found someone who loved her enough to stay with her, without a potion’s help, a father’s love could have changed the outcome just as readily.

it’s interesting to me that later she did confirm that voldy never loved anyone, but not that he was necessarily incapable of loving SOMETHING:

archey: Did voldemort ever love a girl

J.K. Rowling: No, he loved only power, and himself. He valued people whom he could use to advance his own objectives.

there are many muggles i’d put into this category. doesn’t mean they’re not incapable of love. just that they don’t get it because they’ve never been shown it or haven’t been made cognizant of its worth. if you are the most powerful wizard in the world nobody is going to appear your equal; how can you fall in love with an ant? if you’ve been raised in an orphanage and grown up with people fearing your abilities how do you understand the concept of getting close to someone? how do you let your guard down enough to become vulnerable? i think rowling shows pretty clearly that many non-magical factors contributed to voldemort’s cold cold heart, and yes, knowledge of his parents’ “loveless union” would contribute to his shame, loathing of his own background, and lack of compassion— you cannot deny that. but ultimately it’s not having anything substantial in his life to counteract this knowledge that does him in.

i guess this whole misinformation is what happens when people get their facts direct from wikipedia.

ETA: haha, purpleprimate, shared brain much?