No this is not correct, look up modern whole genome pipelines. Standard read lengths are 75-150 base pairs. Whole genome alignment has never been done with BLAS

No this is not correct, look up modern whole genome pipelines. Standard read lengths are 75-150 base pairs. Whole genome alignment has never been done with BLAST or BLAT (this would take an extremely long time). BWA is most commonly used. Running the standard data pipeline on a mouse human mixture will cause many mouse sequences to be aligned to the human genome.