Final answer:
Members of the same species share external and internal characteristics that are developed through their DNA. Organisms with closer relationships share more DNA in common, just like people and their families.
Step-by-step explanation:
Members of the same species share both external and internal characteristics, which develop from their DNA. The closer relationship two organisms share, the more DNA they have in common, just like people and their families. People's DNA is likely to be more like their father or mother's DNA than their cousin or grandparent's DNA. Organisms of the same species have the highest level of DNA alignment and therefore share characteristics and behaviors that lead to successful reproduction.