Female gorillas choosy about which group to settle in — potentially an inbreeding avoidance strategy

Scientists have found that female gorillas shunned troops in which males from their own neck-of-the-woods were present, but opted to join ones in which no males were their close relatives

New 20-year study shows that female mountain gorillas use their social connections when choosing new groups — seeking familiar faces while avoiding childhood males. Picture: Cedric Ujeneza & Jean de Dieu Tuyizere / Dian Fossey Gorilla Fund

The ‘penny catechism’ warned us "not to marry within the forbidden degrees of kindred".

We learned this ominous-sounding phrase off by heart at school, but had little idea what it meant. Nor were our teachers keen to enlighten us as to its meaning.