Dispersal among populations is crucial both for demographic stability and for evolutionary potential of species through the resulting gene flow. In marine organisms, dispersal is assumed to be prevalent during pelagic early life stages. Consequently, pelagic larval duration (PLD) has been proposed as a key driver of genetic population structure of marine species. Despite this prediction, empirical studies have reported inconsistent correlations between PLD and genetic structure. This inconsistency could arise either because PLD is a poor predictor of gene flow or because of differences in methodology, oceanography or sampling design across studies obscure the underlying mechanisms of gene flow. In the present study, we address these issues by using a consistent sampling design for multiple coastal species that differ in PLD. We utilize ddRAD sequencing to analyze our target species, Littorina littorea (common periwinkle), and compare with previously published genetic data (ddRAD and microsatellites) from nine other species, collected through related projects over the last few years. We investigate spatial genetic structure using an isolation-by-distance (IBD) model with pairwise FST-estimates regressed against shortest distances following the prevailing along the coastal ocean current in the study region. We find a significant (p<0.05) correlation between species’ PLD and IBD slopes, with a moderately strong correlation (r2>0.5), These finding supports the notion of PLD as key factor shaping genetic population structure in coastal species. Our findings reiterate genetics as a useful tool for inferring population dispersal in coastal species when potentially confounding factors are eliminated by adopting a consistent sampling design.