To be honest, it's not really for your understanding on what another person considers could be a roleplay killer for them. Maybe they had experiences with teen pregnancy that rubbed them the wrong way and granted the story they told was a little on the what the heck side but nonetheless they still give you an answer. It might not be the one you wanted to hear but regardless it was their answer. They don't have to give a whole essay of an answer if they don't want. Sometimes you just have to move on.And your point is?
I still don't really understand why that'd would kill any roleplay. Even if you're talking about one player suffering from a lack of character variety as a whole (but why specially single out teenage pregnancy in that case?), if that one player is having fun and such a character works with the setting it won't really hurt the rp.
As a quick sidenote, that story paints you in a much worse light than it does her.