a sister company / a brother company

[herbivorie]

In English, "a sister company" is a company that shares the same owners or parent company with another company, isn't it?
Don't you say "a brother company" to mean the same thing? (I wondered about this because we say "a brother company" in Japanese.)

 

[Grumpy]

No. In BrE, the term is always "sister". I don't know why "brother" isn't used.

 

[SoothingDave]

Same in AmE.

Also my city can have a "sister city" in some other country, but there are no "brother cities."