Genesis 42:13

‘And they said, “We, your servants, are twelve brothers, the sons of one man in the land of Canaan. And behold, the youngest is this day with our father, and one is not.”

They try to present a full picture of themselves so as to allay suspicion. They still think of their family in terms of twelve sons a sign that they have not just been able to dismiss Joseph from their minds. This would suggest a sense of guilt and regret.