By nuturing I presume you mean caring for the needs of others, your children. All beings need care in some way or another and to some degree or another. I happen to be naturally nuturing but then again I have my times that I need rest or space for a while. I think a naturally nuturing person tends to see the needs of others and the want for helping them. But sometimes not helping is more helpful. Sometimes helping a little is more helpful. One must try to see clearly anothers needs and not just put their own stuff in it just because they're the type to nuture. I also think everyone has their limits and must maintain balance.
Anyone can learn to be nuturing to a child as long as they actually want to. Nuturing is a matter of love and giving that love from self in a selfless manner. Children need warmth and kindness and calmness, but that doesn't mean we're always going to be so perfect as to be able to give it in such a perfect manner all the time. But kindness and such doesn't necessarily mean giving in to whims or being fluffy or such, it means being good for goodness sake and doing and saying kind things; thoughtfully responding, keeping things light. (at least continually aiming for this)
Balance is key. You may be going from one end of the spectrum to the other and that's why the transition isn't so smooth. Try to practice balance - watch your words and reactions and actions whether you feel nuturing or not. Practice responding after thoughtful consideration and how you want to respond in a calm fashion. This usually just takes a few extra seconds or minutes. No one says you have to respond immediately to anything. I learned this after realizing finally I was saying things I wished I hadn't.
Yes, nurturing attitudes can be learned. The fact is everyone nutures something in their life -- it can be something productive or counter productive. It could be watching tv, it could be kniting, it could be nuturing a particular habit of thought that is good or not so good. So when we begin to think of things in this way perhaps it changes outlooks.