I strongly support a kid to learn photography as there are many benefits in learning. The only downside is the COST $$$...I have kept my film SLR for my kid and hopefully she will revive it some day.
I believe many people will find it not justifiable for a kid to own a $1000+ camera because it may turn into a $1000+ toy. Just have to educate the kid well in appreciating photography and the gears. As what many people have said "There is no bad equipments, only bad photographers..."
Probably someday your cousin will probably outshine many of us in CS. Many people who post in CS are not photographers....they just talk so much but no photos....
interest is subjective.
Some are born with a strong interest for something.
Some are cultivated to have an interest for something.
Some no matter what, also no interest and will never have an interest for something.
So as a parent, you should still see which category your kid lies, just dun force him or her to do something he or she dun like.