Simplify the following text for a Grade 7 native English-speaking person.
Original: This mechanism of sex determination gives rise to what W. D. Hamilton first termed `` supersisters '' who share 75 per cent of their genes on average . Sterile workers are more closely related to their supersisters than to any offspring they might have , if they were to breed themselves .
Simplified: On average , two supersisters have 75 percent of the same genes .