Kim Ceurstemont always knew she wanted to be a mother. In her late 30s and still single, she opted to become pregnant through a donor. She planned to raise her son on her own, but wanted her child to know who their father was. So she chose a donor willing to share his identity. His name was...

As a teenager, Ling Pai had barely settled into her new home, in a new country, when she learned she was losing her sight. She’d been diagnosed with dominant optic atrophy, a degenerative condition with no cure or treatment. Her vision would continue to get worse with every passing year, until...