CHIEF INVESTIGATIVE CORRESPONDENT BRIAN ROSS REPORTS ON DEADLY RIP CURRENTS, ON "20/20," FRIDAY, JULY 22 ON ABC

Also: Three Stories of Unusual Family Relations: -- Couples Who Break the 'Kissing Cousins' Taboo; -- A Female Identical Twin Who Transformed Herself into a Transgender Male; -- Growing up with a Handicapped Sibling

Over the past five years, more than 50 people have drowned off of beaches along the Gulf of Mexico in the Florida panhandle due to deadly rip currents. Yet in Walton County, Florida, where two and a half million people a year from the Midwest and South visit, there are no lifeguards anywhere along the county's 26 miles of beaches -- even though six people died in one day in 2003. ABC News Chief Investigative Correspondent Brian Ross reports that many of the visitors are unaware of just how dangerous these waters can be. Ross asks county officials who advertise their beaches as a perfect, safe vacation, what, if anything, they've done to in fact make the beaches safer. Ross also talks to an expert about how to survive a rip current. The eye-opening report airs on "20/20" FRIDAY, JULY 22 (10:00-11:00 p.m., ET) on the ABC Television Network.

Plus: Kissing cousins...Is marrying your cousin more than just a social taboo? Many people assume that married cousins, especially first cousins, will have kids with birth defects. But as John Stossel reports, a groundbreaking study funded by the National Society of Genetic Counselors revealed the assumptions about cousin marriage may be unfounded. In fact, the parents of one of history's smartest men, Albert Einstein, were cousins, and he too married a cousin. (Originally aired in August 2004)

And: Elizabeth Vargas reports on identical twins who could not be more different. Thirty-five years ago, near Anchorage, Alaska, Juanita and Liana Barbachano were born identical female twins. Now they are brother and sister. Juanita, who transformed herself into a transgender male named Juan, says he knew "that I was really a boy" since the age of three. So how could identical twin girls, conceived from the same fertilized cell, sharing the same DNA, turn out to be so different? Vargas reports on the compelling and often painful journey of Juanita to Juan and the profound questions it raises about what determines human identity: nature or nurture? (Originally aired in November 2004)

Also: ABC News Correspondent Bob Brown reports on an emotional story of growing up with a handicapped sibling, and the lengths to which one sister will go to protect her brother. (Originally aired May 2004)

ABCNEWS.com, the 24-hour news service of ABC News and part of the ABC Internet Group, will provide companion programming to Friday's broadcast.

"20/20" is anchored by Elizabeth Vargas and John Stossel. David Sloan is executive producer.