I'm the only child now because my brother passed away 2 years ago
Oh no I'm sorry to hear that!  Technically, though,  "only child" is generally applied only to those individuals who have never had siblings.
Oh, I didn't know that. 
No worries! Actually, throughout history, only children were pretty uncommon as many families had multiple children.
I wonder why? Maybe because they didn't have condoms
History of condoms
The history of condoms goes back at least several centuries, and perhaps beyond. For most of their history, condoms have been used both as a method of birth control, and as a protective measure against sexually transmitted diseases. Condoms have been made from a variety of materials; prior to the 19th century, chemically treated linen and animal tissue (intestine or bladder) are the best documented varieties. Rubber condoms gained popularity in the mid-19th century, and in the early 20th century major advances were made in
Only child
An only child is a person with no siblings, either biological or adopted. 
Children who have half-siblings or step-siblings, either living at the same house or a different house - especially those who were born considerably later - may have a similar family environment to only children, as may children who have much younger siblings from both of the same parents (generally ten or more years).
Overview.
Throughout history, only children were relatively uncommon. From around the middle of the