Why is it so hard for teenagers to give and receive affection?

So...this was the question posed to me today from one of my older sisters. I wasn't quite sure how to answer at first. It seems I always have a knee jerk reaction to questions such as this but wanted to count to ten before I chose to answer. Plus I wasn't sure if it was simply a trick question on her part!

So my answer was this...when we are teenagers we enter into this transitional phase of our emotional development. We are still figuring out how to articulate emotion. We are uncomfortable in our own skin so how on Earth can we know to give affection and certainly how to receive it.

And you know what...I am still trying to figure this one out at almost 37 years of age!!! So I am not sure how helpful I was in answering her question but I tried to keep it simple! She hasn't responded to me yet so not sure if she agrees or not! Anyone have any opinions on this one??