Gifting someone a thing that could be used as a paternity test at a baby shower would be more than a little rude. And presumably if both parents have already done it why would you need to test the baby?
Before all the privacy concerns, I was considering getting my kids tested, even though my wife and I have both done it.
Mainly so that I could see which genes they picked up from each of us and if they got any new mutations.
Also, a situation that might be somewhat niche -- we had IVF, so it is possible there was a mistake in the clinic and the child wasn't made from us. I read too many stories about IVF clinics where the samples were switched by the employees with their own.
Even more mind blowing, through sheer clerical error, the children that came out of my wife could be mine but not hers!
Given that they look like us we're pretty sure the clinic didn't screw up, and at this point I would keep them regardless, but if I could discover an IVF mistake, the settlement would make for one heck of a college fund.
Gee, how magnanimous of you...