I have found that the format fields for all individuals must only contain the GT tag. If I specify any other tag, some of the genotypes get very odd formats. See the second sample in this example.
#CHROM POS ID REF ALT QUAL FILTER INFO FORMAT trio1_g2-b1-i1 trio1_g2-b2-i1
chr1 752721 rs3131972 A G . PASS . GT:PS 0|1:752721 0:752721|0
chr1 838555 rs4970383 C A . PASS . GT:PS 1|0:752721 0:752721|0
chr1 846808 rs4475691 C T . PASS . GT:PS 0|0:752721 1:752721|0
chr1 854250 rs7537756 A G . PASS . GT:PS 0|0:752721 1:752721|0
chr1 861808 rs13302982 A G . PASS . GT:PS 0|1:752721 0:752721|1
chr1 888659 rs3748597 T C . PASS . GT:PS 1|1:752721 1:752721|0
chr1 894573 rs13303010 G A . PASS . GT:PS 0|0:752721 0:752721|1
chr1 897564 rs13303229 T C . PASS . GT:PS 1|1:752721 1:752721|0
chr1 918573 rs2341354 A G . PASS . GT:PS 0|0:752721 0:752721|0
chr1 990417 rs2465136 T C . PASS . GT:PS 0|1:752721 1:752721|1
chr1 998395 rs7526076 A G . PASS . GT:PS 1|1:752721 1:752721|0
chr1 1018704 rs9442372 A G . PASS . GT:PS 1|0:752721 0:752721|0
chr1 1040026 rs6671356 T C . PASS . GT:PS 0|0:752721 1:752721|1
chr1 1062638 rs9442373 C A . PASS . GT:PS 0|0:752721 0:752721|0
chr1 1097335 rs9442385 T G . PASS . GT:PS 1|1:752721 1:752721|0
chr1 1110019 rs11260542 A G . PASS . GT:PS 0|0:752721 0:752721|0
chr1 1113121 rs12092254 G A . PASS . GT:PS 0|0:752721 0:752721|0
chr1 1130727 rs10907175 A C . PASS . GT:PS 0|0:752721 0:752721|0
chr1 1158277 rs3813199 G A . PASS . GT:PS 0|0:752721 0|0
chr1 1178925 rs12093154 G A . PASS . GT:PS 0|0:752721 0|0
chr1 1203938 rs4018608 T C . PASS . GT:PS 0|0:752721 0|1
chr1 1220136 rs2144440 A G . PASS . GT:PS 0|1:752721 0|0
chr1 1227897 rs3737721 A G . PASS . GT:PS 0|0:752721 0|1
chr1 1258246 rs3845293 A C . PASS . GT:PS 0|0:752721 0|1
chr1 1305561 rs17160669 C T . PASS . GT:PS 0|1:752721 0|0
chr1 1335302 rs1240707 C T . PASS . GT:PS 0|0:752721 0|0
I have found that the format fields for all individuals must only contain the
GT
tag. If I specify any other tag, some of the genotypes get very odd formats. See the second sample in this example.