foster brother/adopted brother?

[englishhobby]

A person's foster brother is someone who the person's parents are looking after as part of your family for a time, without becoming their legal parent.
And if the parents adopt this child (if they become his legal parents), what is the word to combine with 'brother'? Can I say 'He is my .... (adopted?) brother'?

 

[GoesStation]

Yes. He's an adopted sibling.

 

[Rover_KE]

Parents who adopt children say 'Montague is our son'/'Deirdre is our daughter'. They don't mention 'adopted': it's nobody's business but their own, and (ideally) they treat them as equals to their own children.

I hope they all encourage their own children to refer to Montague and Deirdre as their brother and sister so as not to draw attention to the adoption.

 

[Skrej]

However, the expression 'he/she's adopted' can be used for humorous effect, even if it's not true. It's a way of humorously distancing yourself from a family member who's doing something embarrassing. The idea being that the behavior must be inherited from the birth parents because they'd never have learned that from their family.

"Is that your brother up there pole dancing?"
"Yeah, but he's adopted."

"Your family is kind of weird, you know?"
"I'm actually adopted."

My cousins and their parents all frequently publicly deny blood kinship to offending nuclear family members who are guilty of "questionable" public behavior.

My aunt has even gone so far as to refer to her "adopted husband". :-?