I'm so sick of...
Why should someone have 'first-dibs' over someone else just because they're the exact same age? Being the same age as someone doesn't automatically make you the perfect match for them.
You can't just say that they shouldn’t go out with them simply because of their age alone. I've only just turned 20 this January and I'm friends with (but not dating) a girl who is nearly 17 and is the same height as me. If we were dating and I was one year older apparently I'd be annoying or even immoral.
I know a girl (over the internet) who is 20 and is married with someone who's about 34; now that's a difference.
If they are only doing it for the car, money etc, then that'll be annoying as it seems awfully hollow and gold-digging, but otherwise why should the girl not go out with the guy she loves just because he's older? The only disadvantage I see is that when he finally dies she'll be a widow for a long time unless she remarries.
I hope I'm not just being pretentious here, but what do you mean "even their father"? Do you mean that it's worse because she is more used to seeing her father than her uncle, and thus reminds her more of incest? As the age of a father and an uncle is random, they could even be twins.
I dated someone 10 years older than me, that was a problem. Not the age, but she was bipolar in the extreme. I've kinda a biased view, because I've had a 16-year old stepdaughter (changes your perspective; don't think fathers don't know exactly what you're up to... She's 23 now, but stil..
Believe it or not, there was a time when '16 got you 20' (20 year sentance for statutory rape). I guess I'm old-fashioned. a 16-year-old would give me heart failure at my age...