If you're over 20, you should be allowed to fuck whoever you want. I'm an adult, you're going to tell me I can't fuck this dilf or that milf? Ok liberal. The only exceptions have little to do with age, and has to do with specific power relationships, like a student and a professor, a client and an attorney, etc. As someone in their late 20s, I find a lot of older people hot, and I know my female peers also find 40 year men hot, so what am I to do? Tell my 24 year old friend she can't find a 40 year old hot.
I think if you're a 20 year old who wants to fuck a 40 year old that's fine. I think if you're a 40 year old who wants to fuck a 20 year old....well...that's not a crime but....that's kinda gross.