Genesis 5:4
“And the days of Adam after he had begotten Seth were eight hundred years: and he begat sons and daughters:”
KJV
Read in Genesis 5Meaning
Adam's life continues for centuries after Seth, and the text explicitly notes additional sons and daughters without naming them.
Read carefully
The unnamed children show that the genealogy is selective; it is not intended to provide a complete list of every member of the early human family.
Reflection
Biblical genealogies can be historically meaningful while still selecting the persons necessary for the narrative line they are tracing.