Here's a breakdown:
* "Mother tongue" is a metaphor: It's meant to evoke the image of a language being learned from a mother figure, often the primary caregiver. This is because, historically, mothers were typically the ones who taught their children to speak.
* Not always the truth: This isn't always the case. Many children learn their first language from other caregivers, like fathers, siblings, or other relatives. Some children might even learn two languages simultaneously.
* More accurate terms: "First language," "native language," or "L1" are more accurate terms to describe the first language a person learns, regardless of who taught it.
* Importance of the first language: Regardless of who teaches it, the first language a person learns is incredibly important. It's foundational to their cognitive development, identity, and cultural understanding.
So, while "mother tongue" might be a familiar term, it's not always the most accurate or inclusive. It's best to use more precise terms like "first language" or "native language" to be clear and respectful.