It is a well known issue that homozygous IBD can lead to erroneous results in many statistics targeting ancestral reckoning, no matter are we trying to find out ancestry using present-day or ancient samples. Here is a Beagle statistics showing homozygous IBD inside populations using 600000 SNP's. Results are not universally applicable, because of low sample numbers, nevertheless they are valid showing the error possibility of ancestral statistics using any selected data. Homozygous IBD can also reveal bad sample selection (unrepresentative selection). It is also good to notice that random individuals can have large homozygous segments near centromere, still showing relatively low overall homozygous IBD, hence a ROH test is not a good method to show inbreeding.