Two Grandmothers

Riddle: Two grandmothers, with their two granddaughters; Two husbands, with their two wives; Two fathers, with their two daughters; Two mothers, with their two sons; Two maidens, with their two mothers; Two sisters, with their two brothers; Yet only six in all lie buried here; All born legitimate, from incest clear. How can this be?

Answer: Two widows each had a son, and each widow married the son of the other and then each had a daughter.

Source: https://www.riddles.com/index.php/1045

Two grandmothers, with their two granddaughters; Two husbands, with their two wives; Two fathers, with their two daughters; Two mothers, with their two sons; Two maidens, with their two mothers; Two sisters, with their two brothers; Yet only six in all lie buried here; All born legitimate, from incest clear. How can this be? — Two grandmothers by Anonymous v1.

Riddle: Two grandmothers, with their two granddaughters; Two husbands, with their two wives; Two fathers, with their two daughters; Two mothers, with their two sons; Two maidens, with their two mothers; Two sisters, with their two brothers; Yet only six in all lie buried here; All born legitimate, from incest clear. How can this be? Answer: Two widows each had a son, and each widow married the son of the other and then each had a daughter. — by Anonymous v2.