is my wife and her son relationship too close and is he gay?

[cunfussed]

I believe my wife's relationship with her son is too close. We got together when her son was 13 (hes now 18), from the start i thaught he was gay, when i first met him he hanging around with this girl and i said "oh is this your girlfriend" he replied "eww no gross" so i thaught from there he was gay. His relationship with his mum as from when we met has never changed, very close, a lot of hugging, cuddling on sofa, kissing (on lips ONLY lips NO toungue), effectionate taps/squeezing his bum. Not a shy boy to be walking around in his underpants, when he does she whistles to him and says "hey sexy"a bit odd i know. Not that long ago he walked down wearing only his mothers jumper on (it was long on him a few inches above the knee), i instantly thaught to my that he is soo gay, its obviouse

[SocialJustice91]

It sounds like your wife and your son have a very close and open relationship.  Reading your post, it certainly sounds like you are concerned, and perhaps have issues on what your son's personality and behaviour may imply about his sexuality.  It sounds like their relationship may not be the norm, but not abnormal, if that makes sense.  I am picking up that there may be some friction or distance between you and your son.  In your post you did not describe your own relationship with him, I find this interesting.  I am curious about your attitudes regarding your son's perceived sexual orientation.  Would you be accepting of him if he were gay or bisexual?  Would you be accepting of him if he were transgender?  I cannot make assumptions about if he is or isn't and that is not my place to do.  
I have worked with LGBTQ youth and their families in the past.  I can tell you that there is a grief and loss cycle experienced by parents of LGBTQ youth.  I have seen parents whom consider themselves accepting of LGBTQ people have disappointed or denial responses to their own children.  This is rooted in the ideas we have attached to our kids when they are young.  If we have sons, we may fantasize about their lives as adults usually placing ideals such as their future wife, children, job, etc.  as an example.  It is very natural to do as a parent.  If our kids start to show behaviours which are not congruent with those ideas, it can make us uncomfortable.  The idea that your wife is comfortable with your sons eccentric behaviours may leave you feeling isolated, and frankly, feeling a bit off about the whole thing, including her relationship with him.  
I don't like to make assumptions, but I am going to make one now.  You love your kid, and you love your wife.  I do not know if you are in the place to accept having a child whom MAY be gay or perhaps identify as female, only as a possibility (because again, I cannot make that conclusion how he identifies).  My hope is that if that were the case you could accept that.  Although as I mentioned it is natural to feel uncomfortable with the idea.  I hope that your relationship with your wife is strong enough that you can have a discussion with her about this.  It is also natural that their relationship as you describe it can come off as bizarre to you.  Life is full of uncomfortable conversations.  I hope that you can have a meaningful and non-judgmental conversation about this as it sounds like you have some off feelings from the whole thing.  Really, it is about visiting your discomfort about the situation at hand that I think will give you the answer.

[Harv_c]

From what you have provided I would say No and No.  He could be either way.  There are a fair number of people that act this way toward family members, especially moms to sons when the father is not in the picture.
Another question would be, "Why do you see this as an issue?"    

[AnnieBrooke]

Well said, Harv.  It might be that the guy's wife is just playful and thinks it's funny to tease her son about his behind.  My son is 10 and occasionally when he sticks his rear up in the air when wearing only underwear (like, if reaching off the bed for the cat, in other words, nothing intended to be provocative) I'll joke with him about putting his bottom in the air, or give him a light slap on the seat.  The o.p. might just be seeing that level of unceremonious joshing between the two of them.  And I don't know why he would see it as an issue if the son seemed gay, or straight, since it doesn't sound incestuous.  It just sounds like a close relationship where nobody is being very formal.