Haplotype-resolved methylation profiling across three generations reveals principles of human epigenetic inheritance

Epigenetic inheritance is fundamental to human development and disease, yet the mechanisms governing the transmission of DNA methylation across generations remain incompletely understood. In this study, we performed haplotype-resolved, whole-genome DNA methylation profiling in a healthy three-generation Chinese family, leveraging high-depth Oxford Nanopore Technologies (ONT) and PacBio HiFi long-read sequencing, anchored to a proband-specific telomere-to-telomere (T2T) genome assembly. We observed globally conserved bimodal methylation landscapes across all individuals and generations. Stratified analyses revealed clear functional compartmentalization of methylation marks, characterized by distinct hypomethylation in centromeres and hypermethylation in retrotransposons and repetitive elements. Chromosome-resolved analysis of ribosomal DNA (rDNA) arrays demonstrated a domain-specific methylation pattern with hypomethylation in the transcriptional core and hypermethylation in the intergenic spacer, with evidence for age-associated epigenetic drift in the transcriptional core domain. Through de novo identification and validation, we mapped 23 high-confidence imprinting control regions (ICRs) showing robust parent-of-origin-specific methylation, all overlapping known imprinted genes and enriched for regulatory element signatures. Haplotype-resolved X chromosome analysis further uncovered sex- and allele-specific methylation patterns linked to X inactivation dynamics. Together, this pedigree-scale, high-resolution study delineates the landscape and principles of intergenerational DNA methylation inheritance, revealing both conserved and dynamic features shaping the human epigenome.