The timeline information is what reveals who the OT is. If you want to figure it out, then check it.
If you don't want to put the time and effort into opening another tab to check an egg to see if it was bred by you, then maybe Nature/IV hunting isn't for you.
Moving to rejected.
I apologise, but I don't see the logic in this, especially when one could use the same statement against nearly any other feature of the site. "If you don't want to put the time and effort into opening each Pokemon in an individual tab to feed a berry, then maybe massclicking isn't for you."
aaah... pf1 memories XD
Yes, some things should stay difficult (eg: variant/exclusive/legend hunting, melan hunting in general) but I don't see why nature/IV hunting should be one of those things, especially when there's a possiblility for a helpful quality-of-life addition that wouldn't hurt the game's economy or overall difficulty at all.
I hope this makes sense.