Answer
$P(both~same~sex)=\frac{4886}{7285}\approx0.6707$
Work Step by Step
The sample space: $4710+490+89+1735+150+24+50+11+26=7285$ cases. That is:
$N(S)=7285$
Now:
$N(both~male)=4710$
$N(both~female)=150$
$N(both~Unknown~sex)=26$
$P(both~same~sex)=P(both~male~or~both~female~or~both~Unknown~sex)=P(both~male)+P(both~female)+P(both~Unknown~sex)=\frac{N(both~male)}{N(S)}+\frac{N(both~female)}{N(S)}+\frac{N(both~Unknown~sex)}{N(S)}=\frac{4710}{7285}+\frac{150}{7285}+\frac{26}{7285}=\frac{4886}{7285}\approx0.6707$
