If identical twins are genetically identical, does it mean that their DNA is identical too?

I am the father of identical twin boys and one son has well-established skills and experience in searching for DNA clues left behind by suspects at the scene of a crime. While studying forensic science at the University of Durham the subject of his chosen thesis was “Can identical twins really get away with murder?”. He arranged for mouth buckle swabs to be taken from himself and his twin brother under clinical conditions. The subsequent DNA analysis showed their DNA to be the same and an exact and proven match against the 20 different areas of the DNA profile currently recognised worldwide by forensic law enforcement.

Having the DNA alone would therefore be insufficient when trying to solve a crime in which both identical twins were prime suspects. However, fingerprint experts can differentiate between the two siblings from their fingerprints which will have developed differently while in the mother's womb from external pressures that cause slight changes in the flow of the finger tip ridges before they are fixed permanently.
— John Stather, Weybridge, Surrey

Why are the windows on aircraft always placed at such a height that adults can't see out of them without getting a stiff neck?

Most modern commercial aircraft are pressurised and usually the most efficient means of constructing a pressurised fuselage is to have a circle or, occasionally, an oval. This means that the windows are set at the horizontal midway mark on the circumference. To do otherwise would mean that it would be difficult to look down at the Earth's surface, which is the direction most people want to look.

The reason why the passengers' shoulders are high in relation to the windows is that the lower part of the circular cabin is occupied by structures such as the wing box, and by fuel tanks and the holds for baggage and cargo.
— David Wragg, Stoneyflatts, Edinburgh

The fuselages of airliners can be pressurised to, on average, between 5 and 7 pounds per square inch (PSI). This dictates that the windows must be quite small. (Concorde's windows, with about 10 PSI were miniscule).

The ideal location for the windows would be close to the widest part of the fuselage but, because of the lower under-floor freight hold requires much space, the floor is higher than ideal and the passengers are, therefore, located as high as possible, with minimum headroom, in the cabin. This results in the windows in most modern passenger aircraft being below sitting eye level.

In the days of unpressurised airliners, such as the Vickers Viscount, the windows were oval, very large and near sitting eye level.
— Michael S. Church, Spixworth, Norfolk

The fuselage of an aircraft is a beam, carrying loads that predominantly bend it up and down. A beam when bent carries the load by tension stresses in the “convex” side and compression stresses in the “concave” side (the actual curvature is too slight to be detectable). In the middle is a “neutral zone” which carries little or no stress, and that is where windows have to be placed to avoid interrupting the continuity of the highly stressed zones. It is unfortunate that this happens to be where it causes a crick in the neck.
— J.R. Pope, Tisbury, Wilts

What happened to Esperanto? Is it still being taught?
Kenneth Wood, Exeter

Are there birth defects in animals who reproduce with close relatives, eg, fish, tadpoles, lizards?
Mrs B. Harrison, London

Are there any cultures in the world where the handedness is predominantly left rather than right?
Peter Burville, St Margaret's Bay, Dover

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