Does the Buddha deny genetic differences? In MN.98, the Buddha seems to deny the ethnic/racial/genetic differences between humans. He seems to indicate that differences in physical traits between individuals are not determined by birth as in the rest of the animal world. This seems totally contrary to genetics:

I. Humans are genetically part of the animal world and follow the same laws of heritability.

II. Whether we speak of race or ethnicity, there are many identifiable genetic clusters within humanity.

III. Even without going that far it is obvious that between two individuals there will be physical differences according to their genetics (height, eye colors, features, hair, etc). The Buddha seems to deny this completely.

He says for example that the differences in eyes/nose/shoulders, etc., between two individuals are not defined by birth but by convention... this is totally false: children inherit the traits of their parents and two parents with the Asian phenotype do not give birth to an African child by pure chance or convention. I thought it was because he wanted to say that all these genetic differences were conventional and I would have agreed, but it can't be that since he's only saying that for humans and recognizes the validity of these differences for animals and plants... I don't understand this sutta?


  While the differences between these species are defined by their birth, the differences between humans are not defined by their birth. Not by hair nor by head, not by ear nor by eye, not by mouth nor by nose, not by lips nor by eyebrow, not by shoulder nor by neck, not by belly nor by back, not by buttocks nor by breast, not by genitals nor by groin, not by hands nor by feet, not by fingers nor by nails, not by knees nor by thighs, not by color nor by voice: none of these are defined by birth
  as it is for other species. In individual human bodies you can’t find such distinctions. The distinctions among humans are spoken of by convention.
  
  
  The Buddha
MN 98 is about "jati" or "social identity". The Buddha says physical birth or "ancestry" is unrelated to jati; that the jatis are verbal designations assigned due to kamma (actions). 

For example, Michael Jordan's great great grandparents were probably slaves. Where as Michael Jordan was a sporting superstar &amp; billionaire. Jordan was born at Cumberland Hospital in Fort Greene, Brooklyn, to Deloris, who worked in banking, and James R. Jordan Sr., an equipment supervisor. These distinctions of "slave", "banker", "supervisor" vs "basketball billionaire" are not related to physical birth or ancestry. They are related to social kamma (activity). 

Albert Einstein was a German-born theoretical physicist. His parents were Hermann Einstein, a salesman and engineer, and Pauline Koch. The Einsteins were non-observant Ashkenazi Jews, and Albert attended a Catholic elementary school.


  You’re a brahmin by your deeds, Kammunā brāhmaṇo hoti,
  
  and by deeds a non-brahmin. kammunā hoti abrāhmaṇo.
  
  You’re a farmer by your deeds, Kassako kammunā hoti,
  
  by deeds you’re a professional; sippiko hoti kammunā;
  
  you’re a trader by your deeds, Vāṇijo kammunā hoti,
  
  by deeds are you an employee; pessako hoti kammunā.
  
  you’re a bandit by your deeds, Coropi kammunā hoti,
  
  by deeds you’re a soldier; yodhājīvopi kammunā;
  
  you’re a sacrificer by your deeds, Yājako kammunā hoti,
  
  by deeds you’re a ruler. rājāpi hoti kammunā.
  
  In this way in accord with truth, Evametaṃ yathābhūtaṃ,
  
  the astute regard deeds. kammaṃ passanti paṇḍitā;
  
  Seeing dependent origination, Paṭiccasamuppādadassā,
  
  they’re expert in deeds and their results. kammavipākakovidā.
  
  Deeds make the world go on, Kammunā vattati loko,
  
  deeds make people go on; kammunā vattati pajā;
  
  sentient beings are bound by deeds, Kammanibandhanā sattā,
  
  like a moving chariot’s linchpin. rathassāṇīva yāyato.
  
  MN 98