User blog comment:Forestpaw13/An explanation of genetics -- Quarter-bloods/@comment-1158806-20100321012439

A quarter-blood basically is a half-blood, yes. But they're called that simply because both their parents are half-bloods. Quarter-bloods also tend to be a bit more powerful than regular half-bloods, as shown in Taylor Grace-Castellan, Lisa Jackson, Eliza di Angelo, etc.