This resource appears to be designed to build towards this disciplinary core idea, though the resource developer has not explicitly stated so.
Comments about Including the Disciplinary Core Idea
The main objective of the activity is that the learner will explore how genetic make-up is received from both parents and is expressed by traits that can be predicted. The background information makes the connection that an offspring is the result of half of the genes acquired from both parents. The educator has to make the connection that with each offspring the random acquisition of genes produces siblings that will not be exactly alike, even though they are from the same parents. Additional teacher background information on horse coat and eye color can be found at http://colorgenetics.info/equine/eye-color-horses.