My daughters have been shooting since they were 7.
Right now my younger daughter is a dead shot with a .22 - her favorite rifle is the Winchester bolt action my father left me many years ago.
She's also bright enough not to compare her 10-ring shots with my mostly-better-than-5 rings I get with my pistols.
BTW, my older daughter likes Glocks, and hasn't quite forgiven me for trading my last one for an HK.
Oh, and both of them think the Taurus line of pink pistols are gross.
My son is almost 3 months old, but he will be starting out young like I did. Maybe start him out at 4 years old.