Should he be left handed?

I think I'm pretty much ambidextrous. I use my right hand to write, I crochet right handed also when I eat. I pour with my left hand, iron my clothes, and I'm totally left footed. My DD is right handed for everything except eating ?. I really don't think it matters, as long as we are happy doing things our own way.

I use different hands for different activities, and when decorating will paint with whichever is at the best angle for the job in hand - very useful when doing things like window frames

Everyone has preferences for being right or left handed, footed, eyed or eared! They can occur in any combination so it's nothing to worry about.

I have two left-handed daughters, one of whom is very left-orientated, while th other just writes with her left hand and does everything else righthanded.

Both my sons are righthanded but one of them plays left-handed/footed sport.

My dad was totally left handed, but ate right handed with his knife and fork round the normal way
I think lots of people can have a bit of both and as long as he's happy with what he uses, no problem

I use different hands for different things. I have always operated the mouse on my computer with my left hand, among others. I am essentially right handed.

It is called being cross lateral, so it has a name. Relax into it.
www.netdoctor.co.uk/ask-the-expert/pregnancy-and-family/a9703/what-does-crossed-lateral-mean/

I am fairly ambidextrous but I do write with my right hand. Both my parents were left handed and I suspect I started off life as a baby being right handed but my mother taught me to knit, left hand, teacher at school to sew, right hand, tennis, right hand, table tennis, left, darts either. Before I broke my ankle, football would be either. I think I am lucky being so ambidextrous because if either hand is injured, it would not be the end of the world. I have heard of stories where at school the child's dominant hand was tied behind his/her back.

Left footed in football is good. Not so many of them and able to play "on the other side" so to speak.

I have a friend who uses different hands for different things, seems to work fine He writes with his left hand and plays high-standard table tennis with his left hand!

Yes, I have a family member who did pretty much the same as your DGS. No pressure from school or parents to be right-handed. In adulthood they then switched to writing with their left hand!

It may be that your DGS has just found that Life is mainly right-handed and automatically goes along with that for some things.

I'm left-handed and am fairly ambidextrous. Just don't ask me to cut a slice of bread unless you want a wedge!