diff --git a/public/java/src/org/broadinstitute/sting/gatk/walkers/phasing/PhaseByTransmission.java b/public/java/src/org/broadinstitute/sting/gatk/walkers/phasing/PhaseByTransmission.java
index 713b4c8cc..d3ed46ce8 100755
--- a/public/java/src/org/broadinstitute/sting/gatk/walkers/phasing/PhaseByTransmission.java
+++ b/public/java/src/org/broadinstitute/sting/gatk/walkers/phasing/PhaseByTransmission.java
@@ -234,7 +234,7 @@ public class PhaseByTransmission extends RodWalker<Integer, Integer> {
         finalGenotypes.add(father);
         finalGenotypes.add(child);
 
-        if (mother.isCalled() && father.isCalled() && child.isCalled()) {
+        if (mother.isCalled() && father.isCalled() && child.isCalled() && !(mother.isHet() && father.isHet() && child.isHet())) {
             ArrayList<Genotype> possibleMotherGenotypes = createAllThreeGenotypes(ref, alt, mother);
             ArrayList<Genotype> possibleFatherGenotypes = createAllThreeGenotypes(ref, alt, father);
             ArrayList<Genotype> possibleChildGenotypes = createAllThreeGenotypes(ref, alt, child);