Possible Clues:

• Existing from birth, derived from parentage
• Like an inherent characteristic
• Lacking genetic variety
• Characteristic of issue in unhealthy family relationships?
• Rooted by heredity
• It makes one cross to have yeast there, by the sound of it
• One is not cross enough if it's in the loaf, by the sound of it
• In race not finishing, having fallen over; that's natural
• Congenital - unwisely inter-related
• Where there's some dough, by the sound of it, that's not cross enough (6)