The statement "Everyone has a father, but not every father has a son" implies that not all parents are male and that some parents have daughters. This means that option 2, "not every parent is a male," is correct. The statement does not indicate that every father has at least one son, as there could be fathers who have only daughters or no children at all. Therefore, option 1, "every father has at least one son," is not necessarily true. Option 4, "no father has just one son," is not directly implied by the statement and cannot be determined from the information provided. The only information we can gather from the statement is that some parents have daughters, which aligns with option 3. Therefore, option 3, "some parents have daughters," is the correct answer.