when you say "for my son".....you can open an account for a minor as a trust account (same same as regular except they are not 18 and you do it for them - many brokers do it).
If you buy under your HIN then those shares are yours.... and tax liability is yours......
Any future transfers out of your HIN when your boy is 18+ will trigger a capital gains tax event for you.......
you could put a note in your will if under your HIN .......... none of this is advice blah blah.
