Simulation of Chromosomal Regions Shared by Family Members R package ibdsim2 version 2.3.3 Simulation of chromosomal segments shared identical-by-descent (IBD) among pedigree members. Using sex-specific recombination rates along the human genome (Halldorsson et al. (2019) <doi:10.1126/science.aau1043>), phased chromosomes are simulated for all pedigree members. Applications include calculation of realised relatedness coefficients and IBD segment distributions. 'ibdsim2' is part of the 'pedsuite' collection of packages for pedigree analysis. A detailed presentation of the 'pedsuite', including a separate chapter on 'ibdsim2', is available in the book 'Pedigree analysis in R' (Vigeland, 2021, ISBN:9780128244302). A 'Shiny' app for visualising and comparing IBD distributions is available at <https://magnusdv.shinyapps.io/ibdsim2-shiny/>. Software Depends: R (>= 4.2.0), pedtools (>= 2.8.0) Imports: Rcpp, ggplot2, glue, ribd (>= 1.7.1) LinkingTo: Rcpp Suggests: MASS, patchwork, shiny (>= 1.9.0), shinyWidgets, shinyjs, testthat, zip Magnus Dehli Vigeland <m.d.vigeland@medisin.uio.no> Comprehensive R Archive Network (CRAN) Magnus Dehli Vigeland [aut, cre] (ORCID: <https://orcid.org/0000-0002-9134-4962>) GPL-3 2026-08-04 application/tgz https://CRAN.R-project.org/package=ibdsim2 doi:10.32614/CRAN.package.ibdsim2 en-GB