"is it possible to persuade them that they are mentally capable of learning it?"
Depends on why they think they are incapable of doing it. Whatever the reason, it is possible that they do not see value in learning it and putting in effort. It might be that they failed in the past - or never tried because they always assumed they can not do it.
However, if your worry is the kid, then talk about that worry with them directly. Don't go around trying to manipulate them into learning something they do not care about. Just say that you worry about the baby picking up the attitude and thus having less options in life (and growing up less capable as a result). Healthy kids are super good in picking up attitudes like that, so the worry is well grounded.
Your wife might be more open to not make herself less capable then she is in front of kid for the sake of kid then to spend a lot of effort on something she does not care about.
Depends on why they think they are incapable of doing it. Whatever the reason, it is possible that they do not see value in learning it and putting in effort. It might be that they failed in the past - or never tried because they always assumed they can not do it.
However, if your worry is the kid, then talk about that worry with them directly. Don't go around trying to manipulate them into learning something they do not care about. Just say that you worry about the baby picking up the attitude and thus having less options in life (and growing up less capable as a result). Healthy kids are super good in picking up attitudes like that, so the worry is well grounded.
Your wife might be more open to not make herself less capable then she is in front of kid for the sake of kid then to spend a lot of effort on something she does not care about.