This study is a two-iteration design-based research project that investigated how youths' science learning and socio-emotional attitudes toward science were influenced by a summer camp with a personal genetics approach. A multidisciplinary team developed a 2-week camp curriculum that included personal DNA tests, family genealogy projects, and fitness tracker data. The learners included 120 youths, aged 10-14, in six camps held in three sites. Data collection included matched pre- and post-scores for genetic knowledge and self-reported affiliation with science, views of science supports, self-efficacy, and science curiosity scores, as well as youths' daily workbook entries. Our analysis included t-tests, Mann-Whitney tests, Pearson and Spearman correlations, and analysis of variance (ANOVA) with post hoc tests. The findings showed significant science learning gains (related to heredity, genotype, and phenotype) for five of six camp conditions. Also, the youths showed gains in socio-emotional attitudes for both iterations, emphasizing malleability of socio-emotional connections to science. Completing workbook pages was not associated with an increase in knowledge gains or socio-emotional attitudes. This study recommends the inclusion of personal DNA data in summer camp environments to support science learning and increase socio-emotional attitudes toward science. It also suggests structured workbook activities common in schools may not support youths' science learning or socio-emotional attitudes in out-of-school programs. Finally, the study's concluding design conjecture map connects the camps' activities to learners' behaviors to learning outcomes in a way that advances the informal science education field's use of personal data in out-of-school-time programs for adolescents.