How did we become Jewish? Well, we were born into Jewish families. Our father was Jewish, our mother was Jewish. The decision was pretty much made for us. Not that we're complaining.
The decision could have been harder if one of our parents was not Jewish. Or, if we came from a broken family and were raised by a stepparent.
If fairy tales are to be believed, stepparents tend to be evil. They make you do chores. They ask their servants to kill you. They don't take you to balls. They poison you with apples. Etc.
In real life, we're told, stepparents are sometimes nice. Take Daryl Hannah, who loved her stepfather so much that she considers him as her father. And, with her stepfather being Jewish, Hannah, although never formally converted, considers herself Jewish as well.
Sometimes, good things come out of broken families.