I'm doing a research about my family ancestry, and of course, as almost every European and people from the Americas, I have ancestors who belong to nobility and royalty. So I'd like to know until which generation those children of Nobility were still considered part of it. My family is mostly from Spain, Portugal, France and Italy, bit maybe English nobility was similar.
P.s. I remember I saw once a diagram where it showed how if a princess married to a commoner their children were "that kind of title", etc. But I cannot find it anymore :(
To answer your P.S.: The term you have on the tip of your tongue is, “Morganatic marriage”. It doesn’t just apply to royalty marrying commoners, either. If a royal Prince or Princess were to marry, say, a Baron(ess) or perhaps even a Count(ess) the marriage could be deemed morganatic.