His father had lots of children, 4 of which became musicians, of which JSB was the last child, the baby. Barbara Margaretha tried to take the family purse (having already been twice widowed). JSB was “orphaned” but his older brothers were adults. Let’s be real.
(Who gets married and dies 3 months later?)
At the time, many people. Death stalked the land, children were lucky to reach adulthood, women were lucky to survive childbirth, and almost everyone experienced grief and bereavement.
It's all in his music - the manic passion of trying to master a craft against that background, a burning faith in a better future, against constant reminders of the horrors of the present.
It's not just four part counterpoint. There's a lot more going on.
Interesting interpretation of "he was orphaned at 10 and left with nothing and had to go and live with his brother".