Help Me Understand Genetics (MedlinePlus Genetics)
U.S. National Library of Medicine (NIH)
Illustrated primer from the US National Library of Medicine covering DNA, gene variants, inheritance, genetic testing, direct-to-consumer and ancestry tests, Neanderthal DNA, genomic research, and precision medicine, written for non-specialists. Best free, authoritative on-ramp; its DTC testing section explains what consumer results do and do not mean without company marketing.
More resources on Genomics & Personal Genetics
The Genetic Lottery: Why DNA Matters for Social Equality
Behavior geneticist Kathryn Paige Harden explains twin studies, GWAS, and polygenic indices for educational and behavioral outcomes, their limitations and population-specificity, and the ethical and policy questions they raise.
The Infinitesimal
Statistical geneticist Sasha Gusev's essays on heritability, GWAS, polygenic scores, and embryo selection, examining what genetic prediction can and cannot do and where popular and commercial claims overreach. Pairs well with Harden's book as a counterweight.
Population and Quantitative Genetics
Free open textbook from Graham Coop's UC Davis courses covering population structure and ancestry, relatedness, heritability, quantitative genetics, and the genetics behind GWAS and polygenic scores, with R code and interactive apps. Gives the mathematical basis for ancestry inference and polygenic risk that consumer reports skip.
Genomic Data Science Specialization
The standard structured course for how genomes are sequenced and analyzed: six-course Johns Hopkins series on sequencing technologies, sequence alignment algorithms, Python and command-line genomics tools, Bioconductor, and statistics for genomic data. Individual courses can be audited free; the certificate is paid.