Cloning humans used to be science fiction, but now it's entirely possible. And that upsets a lot of people. But what if you could save a child's life by closing a bone marrow donor? Would that make the idea more acceptable. In this hour of To the Best of Our Knowledge, grappling with the new and frightening frontiers in genetics. And, a big-gene hunter tracks down personality in our genes.

SEGMENT 1:

Gina Kolata is a scrience writer for the New York Times and author of "Clone: The Road to Dolly and the Path Ahead." She tells Judith Strasser that the creation of Dolly the cloned sheep was an awesome achievement, and reviews some of the latest news on the cloning front.

SEGMENT 2:

Immunologist William Clark tells Steve Paulson all about telomeres and telomerase and why the news about them is significant, but no fountain of youth. Clark teaches at UCLA and is the author of "The New Healers: The Promise and Problems of Molecular Medicine in the Twenty First Century." Also, NIH geneticist Dean Hamer tells Steve Paulson that about fifty percent of our personality is encoded in our genes and explains the research that makes him think so. Hamer is the author of Living with Our Genes: Why They Matter More Than You Think."

SEGMENT 3:

Simon Mawer is a biology teacher and the author of a novel called "Mendel's Dwarf." The hero is a brilliant geneticist obsessed with finding the genetic mutation which made him a dwarf. Mawer talks with Jim Fleming about how frightening it is to live in a world where genetics mean everything.

Distribution dates:

• week of 01/25/98 - hour 2