I knew a woman, met a man, had a kid. That dad met another woman, who already had a kid, then they had a kid. That woman’s ex man/dad had a kid with another woman. Original man/dad met another woman. She had 3 kids, two different man/dads. They had a kid. Original woman/mum met a man then they had a kid. So first kid has a half brother and half sister. His half brother has a half brother, and another half brother. From his own dad. Also another half brother from the mum… who already had 3 kids!
Messy!