Men/Boys never see a problem in anything. Women/Girls see a problem in everything. Ergo men/boys only communicate when they have something to say or ask. That accounts for a lot of grunting and long periods of silence. Women/girls have a need to stay in constant communication. Thus the high phone bills.

I'm leaning towards gender difference. Sydney has already embraced the "sisterhood" concept of reaching out to the women in her life for reassurance on every issue, although we don't need a reason to just want to "chat". Ryan is trying to establish his independence - teen-age boys don't want to be seen as "Momma's boys" and like to give the impression they can do everything on their own. Underneath it all, the bond between you and each of them is exactly the same. Sounds like they'll both be fine and do well....

Jonathan commuted to College but moved out in the year between grad school and his college graduation. Marisa dormed. She was close enough to sometimes come home to use one of our cars on weekends. During the overlap with Jonathan he sometimes drove up to get or drop off his younger sis. She was in touch via email and text. I gave her the blackberry I never embraced from the 2005 mayoral in which she interned (Sayers as a 16yo she was entrusted with large ban deposits of campaign donations and use of the credit card to get supplies at Staples by the campaign's executive director who trusted very few there.). When Jonathan moved out, text and emails always kept us in touch. We (really Jonathan) even got my mom to accept my old iPhone so she could be in better touch with her grandchildren (they even Skype). We even created a shared family calendar that allow us to add events intended for some combo of parent(s) and child(den). Shared interests play a role in contact as well. Common interest in live shows and music serves as a point of contact with Marisa; Jonathan and I share some interest in hi-tech and he functions in formally as webmaster to the extent something I need to do falls beyond my knowledge set.

This is a lob down the middle. The title should tell you all you need to know. Mars/Venus...Stephen did an excellent job delineating the exact difference. I listen and engage with my wife but when she needs that "girl" thing...she has learned that it is time for her to go out with her girlfriends and deal with that stuff. For those of you that need further instructions, please google "it's not about the nail". This should be required of all teenagers. Instructors should be required to be able to explain this fact and by doing so would cause the divorce rate in this country to plummet. I bet there will be a lot of hits on that!

Agree with most of the above, one thing I would add is don't take it personally. I was one of those who was terrible at checking in at home. I was in a new world and I was trying to kick ass and take names later. My mom was really understanding about that and I will always appreciate it. Doesn't mean that you shouldn't hound him (that will let him know he is loved), lol, but just don't be hurt if he doesn't keep up as much as you'd like. College was unequivocally the most fun time of my life.

Both of my sons are in college and they are very good about communicating when it comes to Gas, finances and food. Above that...not so much. So I follow their twitter accounts and find out most of what I need to know and don't need to know :). No apolgies here---my parents were a hell of a lot stricter.
Now I have my 11yr old daughter who is like a piece of velcro. Even during dinner she leans on my left arm while we are both eating. She cuddles every night and I find it endearing...and my eye is always on the fact that it will not be this way forever...so for those times that I feel suffocated, I just let it go....

Rona, as you know, I'm a parent of boy/girl twins, who graduated college in May. On that basis, I can say, "Yes." ;^) Let's just say that gender contributes to personality traits....

What is his relationship with his natural mother?

My sons were very bad about calling when they were in college. I had a good trick though. I would call but not leave a message when they didnt pick up, which if I had, would have been that I was just calling to say hello. But not knowing why I was calling, and being curious, they always called back when they saw missed call.