An online petition calling for the question to be removed, set up by Mencap campaigner Ciara Lawrence, has more than 500 supporters.
She said: "As someone with a learning disability who is married and thinking about maybe having children in the future I find this question inappropriate, offensive and discriminatory.
"It should not matter who you are when you have children, just that you will love them and do everything you can to raise them in the right way."
"I think OkCupid should immediately remove the question and apologise for any offence it has caused."
A spokesman for OkCupid said: "Our question system is designed to help potential matches understand the interests and values of other users.
"Questions range from mundane to provocative and they specifically allow you to determine your potential compatibility with someone else and to avoid people whose viewpoints you strongly disagree with."
