I do not think there is any particular reason for this. May be from the very beginning your child has been in company of girls mostly and that is why he has been enjoying.

Ha ha ha its opposite with my daughter she loves playing with boys and boyish games. I think we should not be concerned about these at this age. With time things will change.

My first opinion would be that it is too early to get to any conclusion about your child's preference. At this age kids experiment and try all types of things.

If you really want an answer for this at a later stage then it can just be explained with one thing that your son prefers activities like girls and girl plays interests him. This does not mean that your boy is lacking somewhere its just that some boys find boy's game too rough and non verbal while they find girl's games more cooperative and verbal. It may be that your son may get involved in boy's game at a later stage. But it could be that later also he prefers not to be rough world in that case you need to find him a group of boys whose preferences are similar.

Hope I did not confuse you.

Do not make a big issue out of this. I am sure it is just a phase and your child with grow out of it. I am sure your child's curiosity makes him play with girls and their toys.. Didn't we play with our other sex sibling and their toys. My son does love playing with her sister and her toys than playing with his friends and his toys. So would I consider it abnormal. No not at all.