I'm over 20, human. I already have four children to three different women. None of them are here on the station, but it does suggest I'm perfectly capable.
For full disclosure, the only issue I can think of is that I do have bipolar disorder. I hadn't heard of it before coming to the station, but I can share some information about it if you haven't heard of it either. My minimal "research" tells me no single gene is responsible for bipolar disorder. Instead, a number of genetic and environmental factors are thought to act as triggers. Worth chatting to the medical staff about if we decide to proceed.