If these marks are not seen in a Shudra, and if they are not seen in a Brahmana, then such a Shudra is no Shudra, and such a Brahmana is no Brahmana.
शूद्रे चैतद्भवेल्लक्ष्यं द्विजे तच्च न विद्यते। न वै शूद्रो भवेच्छूद्रो ब्राह्मणो न च ब्राह्मणः॥