That's retarded

There are both North Indian and South Indian Brahmins and many of these South Indian chess players were actually Brahmins.
Okay not chess, let's check rest of the metrics
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With cherry picking and defining upper and lower caste out of convince, it's not always the case. For example Jats were historically shudras and lower castes but they literally have the highest steppe out of all Indians.
But in general yes, only shudras would have lower steppe than Brahmins. Explainable because all Brahmins were just migrants from North-West India