I've seen some kids that look very similar to how their parents did as babies/toddlers. One of my friends gave birth to a kid who, even at less than a year old, was the spitting image of his father, so much so it was uncanny. But that's a rarity.They can't. If you use babies' looks as the primary indicator, you'd think that all babies were fathered by Winston Churchill. More than anything, I think all of the "Oh! He's got your eyes! And her ears!" comments are just made out of politeness. (Now, as an aside, it would be truly fucking hilarious if someone said something along the lines of "He's got your eyes, and her ears, and the mailman's nose!")
And ultrasounds are totally out of the question for determining looks.
I've seen people say 'He's got your nose!' and it's like 'okay, but noses aren't fingerprints. Millions of people have that nose too. Calm down.'
Even with an ultra-HD 4D ultrasound taken at 39-40 weeks, you can't really tell how the kid is going to look when they aren't scrunched into a ball floating in their own piss. Even as newborns there's not much way to tell (unless they come out the wrong color or something). Give it a few years, or look at baby photos of Mom and Dad, not photos of them grown up.