Yeah but amphibian and fish cloning had already proven cloning possible, dating back to the 50s and 60s.
Human embryonic stem cells were first "derived" in 1998, apparently, two years after Dolly was born, so in that sense you are correct. However, one was not a development from the other. Researching techs out of historical order is a major part of the game...
These techs only roughly follow real world historical developments - you would end up beelining one or two columns pretty often if you wanted to go along historical route of world wide tech development.
Fun fact:
Vast majority of techs will be researched two eras later.
There is plenty of techs, that can wait one era though.
Excluding religions, punks, and few other techs (Megafauna Domestication, Waterproof Concrete, Lead Glass and Mountaineering) all techs will be eventually researched.
Techs, that won't be researched, if you reach X lifestyle (only listing techs with at least two eras of space):
Classical Lifestyle:
Prehistoric - Feline/Poultry/Elephant/Camelid Domestication, Falconry, Animal Riding.
Medieval Lifestyle:
Prehistoric - Feline/Elephant/Camelid Domestication, Animal Riding.
Ancient - Mummification, Soap/Candle Making, Veterinary Medicine.
Renaissance Lifestyle:
Prehistoric - Camelid Domestication.
Ancient - Mummification.
Classical - Mounted Archery.
Industrial Lifestyle:
Ancient - Mummification.
Medieval - Fire Brigades, Crop Rotation, Commercial Whaling.
Modern Lifestyle:
Renaissance - Oil Painting, Free Artistry, Mine Warfare, Hot Air Balloon.
Those lifestyle techs below have OR requirements.
None to all of those techs might be researched by selecting one OR prereq.
Information Lifestyle <Guided Weapons OR Volcanology OR Space Stations OR Composites OR Extreme Sports>:
Industrial - Emancipation, Meteorology, Lawn/Water/Motor Sports, Realism, Impressionism, Women Suffrage, Cubism, Expressionism, Animation.
Nanotech Lifestyle <Jovian Exploration OR Marine Architecture OR Affective Algorithms or Personalized Health OR Graphene Alloys>
Modern - Biological Warfare, Volcanology.
Transhuman Lifestyle <Cloaking OR Personal Robots OR Lunar Trade OR Designer Microbiology OR Hypothetical Biochemistry or Supercharged Crystallography>:
Information - Planetary Exploration, Solar Propulsion, Jovian Exploration.
Galactic Lifestyle:<Nuclear Pulse Propulsion OR Nanotroids>:
No tech left behind for two eras.
Cosmic Lifestyle: <Neutrino Communications OR Folding Space>:
No tech left behind for two eras.
Transcendent Lifestyle: <Mensiokinesis OR Fantasy Materials OR Grand Unification Biology OR Stable Time Loops OR Cosmic Engineering or Tachyon Communication>:
No tech left behind for two eras.