The term gender comes from the English language and means social gender. The reason why we also use an English-language term for this in this country is because, unlike in German, there are two terms for gender in the English language: In addition to 'gender' as the social gender, 'sex' refers to the biological gender. In German, this linguistic distinction between social and biological sex does not exist, which is why the term gender has been adopted into German usage.
Source: Friedrich Ebert Foundation, 2025, https://www.fes.de/wissen/gender-glossar