It's hard to say just yet at his age. Some of the most masculine men with huge muscles, shaved heads and tattoos are gay, and some men who may act feminine and be interested in fashion are straight. I honestly wouldn't be worried about it too much as he is still so young. If you have daughters and your son is the only boy in the family, he may find girls things more intersting to play with. Some gay adults say they've known since childhood that they knew they were gay, others obviously discovered their sexuality during adolescence. I think the only way to know is when he reaches adolescence. Lastly, just continue to support him in everything he does and love him unconditionally whatever the outcome. :)
My son also likes girl's stuff and pink. Is this a sign of being gay
Hi, it is a normal reaction for him to keep doing it because it feels good. However, the next time he does it, tell him it's not appropriate to do that. Don't become angry with him as you may make him feel like its a bad thing to explore his own body. Simply make it clear he needs to do this when he's by himself, instead of on the cupboards etc (may need to explain privacy).
No i don't think your son will be gay when he's older. It is possible that he feels a close bond with males (because when he's swinging, he's not thinking about boys in a sexual way). He may become excited (again not sexually) and due to the excitement, he gets an erection. I don't think this is a cause for concern. Hope all goes well :)