Hello! Are you or do you know someone who is an only child? As in no brothers or sisters at all?
Hi, no I don't know someone
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
of former Senator Joseph Coniglio, Fuller has said: "My first piece of advice to [Coniglio] would be to forget his entire life as a senator, because now he is simply an inmate. And inmates don't care who you are. No longer will he snap his finger and someone will jump for him. He'll be respectful at all times."
Book.
His book "The Ten Prison Commandments: The Ten Rules You Must Know Before You Enter a County Jail, State or Federal Prison