40 years
Only if they're both consenting adults.
It is perfectly acceptable. They are both adults and well over the age of consent.
Answer It doesn't matter. It depends on the individuals themselves and as long as they are both adults.
you can date anyone of any age, as long as you wait until you are BOTH legally adults for any sexual behavior.
With adolescents 2 or even 3 years may be acceptable. As you get older this difference can, and often does, become greater
No.
you could be any age and date, as they had kids when they were 15.
If you are both are consenting adults then no, a 13 year difference in age is acceptable. However, the relationship would be far more successful if the 13 year difference began at 25 years of age or more with a partner who is 13 years older. If the 13 year difference in age is with too young a person the relationships seldom work out because of maturity problems.
It depends on the age of the younger person. If both are adults, there is no issue. However, if one is a teenager there could be legal issues in addition to developmental ones.
50-63
It depends on the culture and on the families and individuals involved. In many countries, it is acceptable for a 30 year old man to be dating a 15 year old girl. But it must be considered that many of the reasons it's considered wrong in the united states do not exist in other countries. Also in other times... it is becomming less and less acceptable throughout history to date someone with a large age difference. Here in the united states, I'd say it's socially acceptable to most people to date within two years of their own age, but when both persons are out of high school, it's really fair at any age.
Their is no maximum age difference, iguess as long as the younger person is an adult it is fine.