Inheritance as cause

तथा ब्रुवाणम् कुशिकमाह तन्नेति कौशिकः॥

कस्मान्मातापितृभ्यां हि विना षड्धातुजो भवेत॥१६॥

पुरुषः पुरुषाद्गौर्गोरश्वादश्वः प्रजायते॥

पित्र्या मेहादयश्चोक्ता रोगास्तावत्र कारणम्॥१७॥

Translation: When Kushik (Hiranyaksha) said this Kaushika said" No, it is not so. How can an organism be composed of Six Dhatus without Mother and Father? Humans produce human offsprings, cows produce cows and horses produce horses. Diseases like Meha (Diabetes is rough translation of Meha) are known to be caused by inheritance. 

Commentary (Chakrapani): Kushik is another name of Hiranyaksha. If we ignore inheritance then presence of Six Dhatus in all organisms will make all organisms indistinguishable. Use of Adi indicates other diseases like Leprosy, Piles etc.

Commentary (Vishnu): Koushika here points out the important point about individuality of each person or organisms. It is true that every organism is a combination of Material and abstract components. But every organism is unique. This uniqueness is imparted through inheritance. 

Presence of genetically inherited diseases cannot be explained by Six dhatu theory. Chakrapani in his commentary is giving examples which are very interesting. Leprosy is now known to be caused by M.leprii Still susceptibility to infection is different in different communities. Prevalence of leprosy is more in India but Europeans are much more  susceptible to leprosy on exposure. This is due to genetic variation. 

Piles is a very common disease. Probably Chakrapani is referring to congenital piles. For animal models of piles we need dogs. Rodents do not get piles.

Both these examples show clinical erudition of Chakrapani.

Another interesting point in this discussion is Kushik has done the previous argument (Six Dhatus) and Koushika is refuting it. In Sanskrit language Koushika means Son of Kushik. We do not know for sure that the participants in this discussion were father and son but it is a distinct possibility. .