is it true that former and present president's children cannot serve in the military? thank you

Several sons of US Presidents have served in the military. Both Teddy Roosevelt and his cousin, Franklin Delano Roosevelt, had sons who volunteered. Two of Teddy's sons died in France; Quentin was shot down and killed in WWI, and Theodore, Jr. died of a heart attack one month after being one of the first waves to land in DDay. Brother Archibald wad served in both WWI and WWI, and was wounded in in both wars. Kermit fought in both wars. Teddy was a former President at the time of WWI, and, prior to his Presidency, had volunteered during the Spanish-American War, forming the famous Rough R"iders.

Of Franklin's four sons, James served as a Marine in WWII, seeing combat and also fighting behind enemy lines. He rose to Brigadier General, winning the Navy Cross and Silver Star in combat. Elliott Roosevelt was a bombadier in the United States Army Air Forces (USAAF) during World War II. He flew a P-38 Lightning in the North African campaign of November 1942. He attained the rank of Brigadier General in 1945. Franklin, Jr. was a Naval officer who was decorated for bravery in the battle of Casablanca. John, FDR's youngest son, also volunteered during WWII, serving in the Navy. Franklin was a sitting President during WWII.

Dwight D. Eisenhower's son, John, attended West Point, and served in the Army during World War II and the Korean War; he attained the rank of brigadier general in the U.S. Army Reserve. A decorated soldier, Eisenhower found his World War II military career thwarted at every turn by fears for his safety and concern from the top brass that his capture would be an unwanted distraction to his father, the Supreme Allied Commander. Eisenhower wasn't President until after WWII.

I didn't bother to look at earlier Presidents and their children, feeling that enough information is here to show that children of President can, and often do, both serve in the military, and volunteer to serve their country in times of war. Note that Teddy Roosevelt lost a son in WWI, and another son (after Teddy's death) in WWII. All 4 of Franklin's sons volunteered during WWII. Almost all the Roosevelt sons were decorated officers, and at least all but one saw combat.

There is nothing to prevent George bush's daughters from serving during this war, at least, no law or rule or regulation prevents them from serving.