It might not be advisable to rely on biochemical evidence alone when

Organisms are based on the the central dogma of molecular biology that involves DNA replication, transcription to mRNA, and translation to proteins. Biochemical evidence alone, in the context of evolution, is not sufficient to determine ancestry as DNA is a very conserved molecule. Similarities of two or more organisms in DNA does not mean they are closely related or share the same ancestor; on the other hand, differences of two or more organisms in DNA does not mean they share different ancestors.