A little makeup to create fake ear seams. Eye color, obviously prescription novelty contacts, because why not. “Coolest grandpa.”

And hair colors, not an issue. So many girls with amazing dye jobs in the area. Pure white and pure black, not even an issue.

Learn the vulcan solute and people wont question the ears.

Go get Kate. Or state that you’re their grandpa. It’s as close to accurate as possible, though the ear thing would still raise a few eyebrows.