Ser de buena cuna

Ser de buena cuna
 

it means that your origins are good, that your were born in the seno of a good family. English?

To be of good birth
To be of noble birth (ilustre cuna)
To be of humble birth (humilde cuna)

Also to be from a good family.

Not also.

Ser de buena cuna, significa ser de buena familia.

Ser de cuna ilustre = ser de familia de/con alcurnia.

Ahora si uno habla de una cuna cualquiera, tal como en inglés, you are talking about the cradle itself.

You can say : To come from solid stock.

I thought about that and decided it connotes someone of inferior class. Maybe that's just influence from Wodehouse, though.

I think I agree, even without Wodehouse. Solid stock is understood as reliable, conservative, with connotations of inferior class. Not quite the same.