When it comes to proteins, that's a given. No duh we're related. Proteins are coded by DNA. Those animals with proteins closer in structure (the amino acid order and possibly folding) are more closely related to us. why? The closer the DNA, the closer the proteins will be.
Peptides, which I believe you are using for the term amino acid (if not, then you refer to peptide bond, the bond between two amino acids, or polypeptide, which is a chain of amino acids), are also based off of DNA. AAA, TTT, CCC, GGG are four amino acids. everyliving thing on this planet uses these bases (except in RNA, where the T is replaced with U). amino acids won't prove relatedness except for the fact that we all have DNA.
Basically, the answer to your question, though, is yes.
abe:
the reason water can't prove any relatedness is because it is not derived from DNA.
Edited by kuresu, : No reason given.
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