data a1;
input Rep Gen sire dam animal y1 y2 y3;
cards; 
1
1
2
10001
20001
341.561
140.218
-1.32
1
1
3
10002
20002
316.23
143.202
-0.598
Proc sort;by gen;
proc means noprint;by gen;var y1 y2 y3;
output out=m1 mean=y1 y2 y3;
proc print; run;