It was my understanding that when chromosomes pair up, one half of each pair comes from the father, and the other half, from the mother. Can one chromosome from the mother pair with another chromosome, from the same mother?
“Can one chromosome from the mother pair with another chromosome, from the same mother?”
Yes, trisomies do occur, but this is an issue completely unrelated to anything in this thread. Even if chromosomes pair up the way you think, it is still unlikely the baby will have 50% of its legal father’s genes. And it is possible it will have 0%. The diagram I posted to you illustrates this.