A study conducted by Teagasc has shown that 53% of triplet lambs are sired by different rams. Research of its kind has never been undertaken previously in any global sheep population.

The phenomenon is called heteropaternal superfecundation (HS), involving separate mating events with two or more rams, leading to the fertilisation and implantation of two or more eggs during the same heat. This results in the birth of two or more sibling lambs sired by different rams.