Final answer:
The purpose of the experimental design in studying triplets with older sisters of the same age, all adopted, is to analyze the influence of genetics versus the environment in their development, providing insights into the aspect of nature versus nurture.
Step-by-step explanation:
The experimental design purpose of having each triplet with an older sister, all the same age and all adopted, likely pertains to understanding the influence of nature versus nurture in human development. In biology, researchers study identical twins or triplets along with their adoptive siblings to gauge the impact of genetics (nature) as opposed to the environment (nurture) they are raised.
Adoptive parent-child pairs, along with similarly aged unrelated children raised together, provide a unique environment to observe how genetic relations and the socialization process affect temperaments, preferences, and abilities.
Such studies can encounter limitations, such as twins being raised very differently or potential confusion between identical and fraternal twins. Furthermore, the sample sizes for such research are often small. Notwithstanding these challenges, adoptive siblings who are closely related genetically but raised in distinct social environments offer valuable insights into human behavior and development.