Final answer:
The sentence suggests that despite a common heritage, the British people treat the colonists unjustly.
Step-by-step explanation:
The sentence "They too have been deaf to the voice of justice and consanguinity" suggests that despite a common heritage, the British people treat the colonists unjustly. The phrase "deaf to the voice of justice and consanguinity" implies that the British are ignoring the pleas for fairness and unity from the colonists. This indicates that the British disregard the bonds of kinship and fairness when it comes to their treatment of the colonists.