According to the 2002 edition of the Guinness Book of Records, the biggest age difference between two siblings is 41 years. Elizabeth Ann Buttle had her daughter when she was 19 years old, in 1956. She had her son when she was 60 years old, in 1997.
Around age 25, the average woman’s fertility is at its highest. But most women can get pregnant on their own until they are 41 years old. Rajo Devi was the oldest woman to ever give birth. She had her daughter when she was 70 years old. She got pregnant with the help of a donor egg that was fertilised with her husband’s sperm in a lab.