Thread:Janus100/@comment-25205238-20180526164909/@comment-27794543-20180526215705

No. Recessive trait means that neither parents has to be Nightblood.

While genetics can be quite complicated, if we're talking about a simple single-gene trait, it means two Nightblood genes are required for a person to be Nightblood. If they have one Nightblood gene, they have normal blood but are carriers for the trait. If they have zero Nightblood genes then they have normal blood and are _not_ carriers. For a Nightblood child to be born, they must receive a Nightblood gene from both parents (that means both parents must be either carriers or Nightbloods). Since Nightblood carriers (i.e. people with normal blood but with a single Nightblood gene) are much more common then Nightbloods, Nightbloods children are likely to have non-Nightblood parents.

I'm not here to teach you genetics. If you're interested in the topic, google it (or open a biology/genetics textbook). e.g.
 * http://knowgenetics.org/934-2/
 * https://biologydictionary.net/recessive-trait/
 * https://www.urmc.rochester.edu/encyclopedia/content.aspx?ContentID=P02142&ContentTypeID=90