Paralogous genes have the same function and have sequence identity while residing in the same organism (opposite of orthologous genes). Humans have other globins as well as the famous haemoglobin, most expressed during their time in the womb. So delta globin and haemaglobin are paralogs.

Often occurs due to gene duplication, which can lead to pseudogenes. Indeed, there are globin pseudogenes which are not expressed, and are subject to neutral drift.

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