Aggression in group-housed pigs is a welfare concern, which can negatively affect production. Skin lesions are reliable indicators of aggression, and are moderately heritable, suggesting that selective breeding may reduce aggression. To further understand the genetic control of behavioral traits, such as the aggressive response to regrouping, associated single nucleotide polymorphisms (SNP) can be identified within the genome, and the region in which these SNP are located can be related to known genes. To investigate SNP associated with aggression, 1,093 purebred Yorkshire pigs were strategically remixed into new groups of familiar and unfamiliar animals at 3 life stages and lesion scores were recorded. Genomic best linear unbiased prediction (GBLUP) models were fitted for each trait. The genetic additive effect was obtained from a genetic relationship matrix constructed from the 50,924 SNP. Single Nucleotide Polymorphism effects and their variances were estimated from the GBLUP objects. Single Nucleotide Polymorphisms that were associated with a significant portion of the trait variance were identified for lesions to the anterior (3 SNP, FDR < 5%) and central (1 SNP, FDR<5%) portions of the body in grow-finish pigs. These SNP were located on chromosome 11, suggesting chromosome 11 contains a region explaining variation in lesion scores that should be further explored to identify genes underlying biological control of aggression.